Tinsel cord



March 9, 1943.

1. E. GAVITT TIN'SEL CORD Filed Sept. 14, 1940 COPPER C 0PPE RI /9'ILI'ER PLATED cop/ 5R JYTHE TIC MATERIAL mmvroa [6&{5 5 fa'lar'l/ M m ATTORNEYS.

mw mm Wm WM 0 Patented vMar. 9, 1943 TINSEL CORD Lester E. emu,Brookfleld, Mass; assignor to Gavitt Manufacturing Company, acorporation of Massachusetts Application September14, 1940, Serial No.356,762

3. Claims.

Th s invention relates to a cord of that type frequently used onacoustic instruments, one example being for assisting those hard ofhearing and of the type which will be worn for a considerable length oftime by the person, and another example being for microphones.

The invention has for one of its objects to provide a light weight cordof greater tensil strength than that usually appearing on the market atthe present time.

Anotherobject of the invention is to provide a cord which will beresistant to perspiration and to the oil and acids of the skin andtherefore one which will last longer by freedom of deterioration fromthese causes.

Another object of the invention is to provide a cord which will beextremely flexible and one which at the same time will be resistant toabrasion by the flexibility of its parts one on the other or fromoutside abrasion with which it may be contacted.

Another object of the invention is to provide a cord having all of thesequalities of a minimum outside diameter and one light in weight so as toprovide a .minimum pull upon the instrument attached to the ear.

With these and other objects in view, the invention consists of certainnovel features of construction, as will be more fully described, andparticularly pointed out in the appended claims.

In the accompanying drawing:

Fig. 1 is a perspective view illustrating the use.-

to which the cord may be placed;

Fig. 2 is a perspective view of a piece of round wire having a platedsurface;

Fig. 3 is a section on line 3-3 of Fig. 2;

Fig. 4 is a perspective view of the plated ribbon after the same hasbeen flattened;

Fig. 5 is a section on line 5-5 of Fig. 4;

Fig. 6 shows this plated ribbon of Fig. 4 wrapped about a core; v

Fig. '7 shows several of thestrands of Fig. 6 twisted together;

Fig. 8 shows a coating about the twisted strands of Fig. '7; 1

Fig. 9 shows the structure of Fig. 8 with a braided covering applied;and

Fig. 10 is a sectional view on line Hl-l0 of Fig. 9 on a still greaterenlarged scale.

In the use of instruments for assisting in hearing, it is exceedinglydesirable that the cord may be made of light-weight material and yethave considerable-tonsil strength and also be of such material that theperspiration or the oil and acids given off by the skin will notdetrlmentally aflect the same, while the cord will be resistant toabrasion. The usual cord which has heretofore been provided on themarket consisted of a plurality of strands eachwith a cotton core whichlacked the tensil strength in a small diameter which was desirable.Also, the cord usually was covered with a material such as rubber whichi was attacked by the acids of the skin which soonrotted the cord andthe core thereof. In order that the cord might be strong enough, thesize of the cord had to be increased. To avoid these disadvantages Ihave provided strength in the core and built up this strength byproviding an outside covering sheath of a strong material which willaccomplish this result. I have further provided an encasement for thestrands which are resistant to the acids and oil of the skin and have sotreated the covering that it is exceedingly resistant to abrasion, allof this being more fully described hereinafter.

'With reference to the drawing, [2 designates the core of one of thestrands which will be of a material which is many times stronger intensil strength than the cotton which is usually provided at thislocation and yet will be of no greater diameter and no greater weight.Material which I have found suitable is Nylon. Nylon is a syntheticfilament more fully set forth in Patent 2,130,948, dated September 20,1938, and referred to therein as polyamide obtained by condensationpolymerization from diamine and dibasic carboxylic acid.

A solid copper wire I3 is plated with silver as at H and is rolled intoa fiat ribbon form, as shown at l5 in Figs. 4 and 5 and is then wrappedhelically about the cord it, as shown in Fig. 6, throughout the lengththereof. The strands thus wrapped, designated generally ii, are twistedtogether, as shown in Fig. '7, at ll. and then suchcord is embedded inan oil-resistant extruded covering, such as Neoprene, l8 which willpermeate through all of the twisted strands to cause them to besubstantially embedded in a solid mold material. Neoprene is apolymerized chloroprene.

This Neopren'e" is selected because of its resistance to oils and acidsand its waterproofing properties and is found to b much better thanrubber or latex, which under some conditions might be used. A substitutefor this "Neoprene would be some synthetic organic substance commonlyreferred to as synthetic resin which would have substantially thewater-resistant and oilresistant properties of Neoprene and also possessthe flexibility which is necessary to a cord of this character, and atthe same time provide longer wearing qualities for the cord. Such asynthetic organic sheathing would not necessarily require a furthercovering of Nylon braid as the surface of the resin presents anattractive appearance and is especially resistant to abrasion. TheNeoprene used will be extruded onto the core and kept at a minimumdiameter so as to just cover each of the strands to provide a casing.

After this extruded covering is placed on the cord, I treat its surfaceI! with a wax of any good insulating properties such, for example, ascerease wax. Cerease wax is a pretolatum type of wax having a meltingpoint of 155 F. A braid is then placed upon the cord so covered. Thisbraid is designated generally 20 and will be formed of yarn of a strongtensil strength and small diameter such, for instance, as Nylon. Afterthe wire is so covered, it is passed through a steam bath which causesthe braid to absorb wax which is placed upon the covering I 9 whichimpregnates this braided covering and causes a sufficient amount of waxto extend through each of the interstices of the braid and about theouter surface so that the braid is exceedingly wear-resistant. Further,the end of the cord it cut will not fray because of this wax and heattreatment which has been given it.

Incases where the cordis to be used for a microphone, instead of placinga braided covering over the insulating material, the covering will be abraided copper shield over the conductor and then a heavy wall ofhigh-grade rubber insulation will be placed over the braided coppershield.

The structure above described has the advantage oi resisting heat to anextent enabling soldering of the tinsel strand without charring of thecore, while the wax film prevents fraying of the covering and increasesits resistance to wear to a considerable extent.

I claim:

1. A hearing aid cord comprising a plurality of twisted tinsel strandsembedded in an over all covering of polymerized chloroprene with acovering of fabricated strands of a polyamide obtained by condensationpolymerization from diamine and dibasic carboxylic acid, said coveringbeing coated with a wax film.

2. A hearing aid cord comprising a plurality of twisted tinsel strandsembedded in an over all covering of polymerized chloroprene with acovering of fabricated strands of a polyamide obtained by condensationpolymerization from diamine and dibasic carboxylic acid, said coveringbeing coated with a wax film, each tinsel strand having a core of apolyamide obtained by condensation polymerization from diamine and dibasic carboxylic acid.

3. A hearing aid cord comprising a plurality of twisted tinsel strands,each strand having a core of a polyamide obtained by condensationpolymerization from diamine and dibasic carboxylic acid wrapped with ametallic ribbon, and said strands being embedded in aperspiration-resistant moldable electrical insulating material.

LESTER E. GAVITT.

